The genes for gamma globin are examples of genes with strict tissue specific and developmentally specific patterns of expression. Our laboratory has found that a fragment of the promoter region of the gamma globin gene is critical for appropriate regulation of expression. Using extracts of nuclear proteins from the human erythroleukemia K562 cell line, we have found that there are several regions within the promoter which interact with potential transcriptional regulatory proteins. The proteins which bind to these regions are being purified and mutant promoters which contain ablated protein binding sites are being evaluated in a variety of transcriptional assays.